Micro-kinetics of dibenzyltoluene liquid organic hydrogen carrier reactions over alumina-supported nickel catalyst

As the global shift towards green energy accelerates to reduce CO 2 emissions and address the greenhouse effect, this study highlights the crucial role of hydrogen storage and transportation. This research investigates the hydrogenation of dibenzyl toluene (DBT), a liquid organic hydrogen carrier, alongside a solution containing dibenzyltoluene (DBB) and dibenzylethylbenzene (DBEB), utilizing cost-effective 5 wt% Ni/Al 2 O 3 catalyst. Laboratory-synthesized catalysts with 5-10 wt% Ni/Al 2 O 3 were evaluated and compared against commercial catalysts where much higher performance was achieved using our catalyst. The impact of various experimental parameters, including temperature, pressure, catalyst mass, and initial LOHC concentration, was thoroughly explored (>1600 exp. points). A micro-kinetic model was developed for a commercially available 5 wt% Ni/Al 2 O 3 catalyst, and recycling tests were performed to assess the catalyst's activity and longevity. The results indicate that the activation energies for the hydrogenation of DBT range from 60 to 79 kJ/mol, with the first step demonstrating the highest activation energy. Furthermore, kinetic parameters for the remaining components in the reaction mixture were defined. The model encompasses all reaction conditions, incorporating the number of metallic sites representing the catalyst's active sites, thereby providing a description of the experimental results and facilitating advancements in catalyst synthesis and the potential for LOHC utilisation.